The present invention relates to an improved liquid energy absorber device having a high spring rate and short travel for use in applications having limited space, such as in the suspension of an industrial inplant truck.
By way of background, an industrial inplant truck used in warehouses needs a spring type of suspension system to absorb impact from irregularities in the floor, such as bumps and floor joints. In trucks of this type, the axles and frames are of established designs and they normally use coil springs which have a low spring rate to attenuate impact. This relatively low spring rate was dictated by the limited space for the spring and the physical parameters of the spring material. The foregoing caused the spring to have long travel, which was highly undesirable because it resulted in unacceptable pitching of the truck with the attendant potential for spilling its load. Therefore, in the past the compression of the spring, of necessity, was limited to short travel by positive stops to achieve stability against excessive pitching, and this, in turn, many times resulted in bending or breaking of the truck axles due to bottoming. Furthermore, the shock of the bottoming of the frame against the axles sometimes caused rupture of the batteries used to power the truck. In contrast to the use of prior springs having a low spring rate with long travel, it is desirable, in inplant industrial trucks, to have a suspension which has a high spring rate which will attenuate impact and which will have a short travel which will obviate excessive pitching. However, in view of the fact that there is limited space for the springs in inplant industrial trucks, the desired objective has been incapable of achievement in the past.